Adaptive Coding Modulation in Regenerative Satellite Systems
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Solution Overview
Problem
Adaptive coding and modulation (ACM) techniques have not been applied in regenerative satellite systems, which lack efficient methods to adapt modulation and forward error correction (FEC) coding to link conditions, limiting their ability to optimize signal quality and capacity.
Innovation Solution
Implementing ACM on both the uplink and downlink in regenerative satellite systems by estimating the uplink modulation and coding combination (ModCod) at the terminal based on received signal quality, and using packet headers to indicate the downlink ModCod for the regenerative satellite to remodulate and reencode packets, thereby reducing the satellite's hardware and software requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ACM is implemented in regenerative satellite systems with full digital processing, then link capacity and signal quality are improved, but satellite hardware complexity and processing requirements increase
Solution Approach 1:
The patent segments the ACM functionality into two parts: the regenerative satellite performs demodulation and decoding, while the ground terminals perform encoding and remodulation. This segmentation allows the satellite to achieve ACM benefits without requiring full digital processing capability, thereby reducing hardware complexity while maintaining link capacity improvements.
Solution Approach 2:
The patent extracts the complex encoding and remodulation functions from the satellite and relocates them to the ground terminals. The satellite only needs to perform demodulation and decoding, which are simpler operations. This extraction of complex functions from the satellite resolves the contradiction by maintaining ACM performance while reducing satellite hardware complexity.
2Adaptability or versatility
If the satellite performs full demodulation, decoding, encoding, and remodulation, then link adaptability is improved, but processing time and computational load increase
Solution Approach 1:
The ground terminals perform encoding and prepare the modulated signal before transmission to the satellite. This preliminary action allows the satellite to receive pre-encoded signals that require only demodulation and decoding, significantly reducing processing time while maintaining full link adaptability through the ground-based encoding operations.
3Productivity
If regenerative satellites use digital on-board processing, then frequency efficiency is improved, but device complexity increases
Solution Approach 1:
The ground terminals perform the complex encoding and remodulation functions that would otherwise require sophisticated satellite hardware. By copying these functions to the ground-based equipment, the system achieves frequency efficiency benefits from digital processing while the satellite hardware remains relatively simple, only requiring demodulation and decoding capabilities.
Data Source
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AI summary
Techniques are described for implementing adaptive coding and modulation (ACM) in regenerative satellite systems to adapt the modulation and/or FEC coding of transmitted waveforms to the conditions of the link. In one implementation, ACM is implemented on an uplink from a terminal to a regenerative satellite (540). In this implementation, an uplink modulation and coding combination (ModCod) is estimated by the transmitting terminal (520) based on the quality of signals received from the regenerative satellite on the downlink. The regenerative satellite may reencode and remodulate the packet using the ModCod indicated in the field of the packet header.